First Use of Fragile Geologic Features to Set the Design Motions for a Major Existing Engineered Structure

2021 ◽  
Author(s):  
Mark W. Stirling ◽  
Elizabeth R. Abbott ◽  
Dylan H. Rood ◽  
Graeme H. McVerry ◽  
Norman A. Abrahamson ◽  
...  
Keyword(s):  
Response Spectrum ◽  
Hanging Wall ◽  
Safety Evaluation ◽  
Field Measurements ◽  
Exposure Dating ◽  
Preliminary Version ◽  
Dam Site ◽  
The Mean ◽  
Design Earthquake ◽  
Formal Design

ABSTRACT We document the first use of fragile geologic features (FGFs) to set formal design earthquake motions for a major existing engineered structure. The safety evaluation earthquake (SEE) spectrum for the Clyde Dam, New Zealand (the mean 10,000 yr, ka, return period response spectrum) is developed in accordance with official guidelines and utilizes constraints provided by seven precariously balanced rocks (PBRs) located 2 km from the dam site and the local active Dunstan fault. The PBRs are located in the hanging wall of the fault. Deterministic PBR fragilities are estimated from field measurements of rock geometries and are the dynamic peak ground accelerations (PGAs) required for toppling. PBR fragility ages are modeled from B10e cosmogenic isotope exposure dating techniques and are in the range of 24–66 ka. The fragility ages are consistent with the PBRs having survived at least two large Dunstan fault earthquakes. We develop a PGA-based fragility distribution from all of the PBRs, which represents the cumulative toppling probability of a theoretical random PBR as a function of PGA. The fragility distribution is then used to eliminate logic-tree branches that produce PGA hazard curves that would topple the random PBR with a greater than 95% probability (i.e., less than 5% survival probability) over a time period of 24 ka (youngest PBR fragility age). The mean 10 ka spectrum of the remaining hazard estimates is then recommended as the SEE spectrum for the dam site. This SEE spectrum has a PGA of 0.55g, which is significantly reduced from the 0.96g obtained for a preliminary version of the SEE spectrum. The reduction is due to the combined effects of the PBR constraints and a substantial update of the probabilistic seismic hazard model. The study serves as an important proof-of-concept for future applications of FGFs in engineering design.

Earthquake Response Analysis and Safety Evaluation of Haokou Gravity Dam

2013 ◽  
Vol 671-674 ◽  
pp. 1394-1398 ◽  
Author(s):  
Fan Yang ◽  
Zhen Zhong Shen ◽  
Kai Min Chu ◽  
Xi Yao Zhao
Keyword(s):  
Response Spectrum ◽  
Safety Evaluation ◽  
Gravity Dam ◽  
Response Analysis ◽  
Dam Foundation ◽  
The Maximum Principle ◽  
Calculation Results ◽  
Set Up ◽  
The Stability ◽  
Design Earthquake

According to the actual engineering conditions of Haokou RCC Gravity Dam, the 3-D FEM model of the typical overflow dam section and its foundation is set up. Using the response spectrum method, the responses of earthquake acceleration, displacement and stress of the dam and their distribution laws were studied under the seismic loading, and the anti-sliding stability of dam is also analyzed. The calculation results show that under the design earthquake condition, the maximum principle stress response of dam body is 2.26MPa, which appears at the dam heel. The safety factor of stability against sliding on the face of the dam foundation is 1.43 and the stability against deep sliding is 3.2. So this dam section can meet the strength and stability requirements of standard, its earthquake-resistant safety could meet the requirements of standard.

Seasonal Changes in the Water Relations of Eucalyptus behriana F. Muell. And E. microcarpa (Maiden) Maiden in the Field

1984 ◽  
Vol 32 (5) ◽  
pp. 495 ◽  
Author(s):  
BA Myers ◽  
TF Neales
Keyword(s):  
Water Potential ◽  
Water Relations ◽  
Rainfall Intensity ◽  
Field Measurements ◽  
Canopy Conductance ◽  
Laboratory Studies ◽  
Short Term ◽  
The Mean ◽  
Type Response ◽  
Vapour Pressure Difference

Field observations of some parameters of the water relations of the two eucalypt species E. behriana and E. microcarpa in dry sclerophyll, mallee and woodland vegetation were made at three sites from 1980 to 1983. The mean ( n = 519) water potential measured at dawn (Ψdawn) was -3.07± 0.01 MPa and fluctuated seasonally with rainfall intensity over the range -2.0 ± 0, 1 to -4.4 ± 0.1 MPa ( n = 30). Both species behaved similarly and some osmotic adjustment took place. Mean leaf conductance (gs) varied between 0.151 ± 0.006 and 0.003 ± 0.001 mol m-2 s-1 . Maximum daily values of gs were linearly related to Ψdawn as it fluctuated seasonally. The slope of this linear regression was not significantly different from that relating these values of gs and Ψ, when both were measured concurrently. There were thus no indications of a distinction between the responses of gs to long- and short-term fluctuations of Ψ or of a threshold-type response of gs to Ψ. Field measurements indicated that gs was decreased at high values of vapour pressure difference (Δe). In laboratory studies with seedlings of the two species gs decreased from 0.5 to 0.1 mol m-2 s-I as Δe increased from 0.5 to 3.0 kPa. Leaf and canopy conductance were the predominant plant determinants of transpiration rate (Er) in this type of vegetation which has the capacity to restrict Et via the effect of water potential (Ψ) on gs and also by the response of gs to Δe. Some of the water relations parameters of E. behriana indicated that this species was better able to withstand drought than was E microcarpa.

On the Combined Effect of Mean Flow and Acoustic Excitation on Structural Response and Radiation

1997 ◽  
Vol 119 (3) ◽  
pp. 448-456 ◽  
Author(s):  
A. Frendi ◽  
L. Maestrello
Keyword(s):  
Mach Number ◽  
Response Spectrum ◽  
Structural Response ◽  
Harmonic Excitation ◽  
Two Dimensions ◽  
Physical Problem ◽  
Acoustic Excitation ◽  
Mean Flow ◽  
Power Spectral ◽  
The Mean

Numerical experiments in two dimensions are carried out in order to investigate the response of a typical aircraft structure to a mean flow and an acoustic excitation. Two physical problems are considered; one in which the acoustic excitation is applied on one side of the flexible structure and the mean flow is on the other side while in the second problem both the mean flow and acoustic excitation are on the same side. Subsonic and supersonic mean flows are considered together with a random and harmonic acoustic excitation. In the first physical problem and using a random acoustic excitation, the results show that at low excitation levels the response is unaffected by the mean flow Mach number. However, at high excitation levels the structural response is significantly reduced by increasing the Mach number. In particular, both the shift in the frequency response spectrum and the broadening of the peaks are reduced. In the second physical problem, the results show that the response spectrum is dominated by the lower modes (1 and 3) for the subsonic mean flow case and by the higher modes (5 and 7) in the supersonic case. When a harmonic excitation is used, it is found that in the subsonic case the power spectral density of the structural response shows a subharmonic (f/4) while in the supersonic case no subharmonic is obtained.

In situ creep of frozen soil, Fenghuo Shan, Tibet Plateau, China

1995 ◽  
Vol 32 (3) ◽  
pp. 545-552 ◽  
Author(s):  
B. Wang ◽  
Hugh M. French
Keyword(s):  
Key Words ◽  
Power Flow ◽  
Field Data ◽  
Field Measurements ◽  
Frozen Soil ◽  
Tibet Plateau ◽  
Soil Creep ◽  
Extreme Variability ◽  
The Mean

Field measurements of frozen soil creep in the upper 3.0 m of permafrost indicate that creep occurs in both winter and summer. Between 1992 and 1993, the mean rate of creep ranged from 0.44 cm at 1.6 m depth to 0.16 cm at 2.8 m depth but there was extreme variability. Creep parameters n and A, as defined by the power flow law, were calculated from field data. Parameter n ranged between 1.96 and 2.29 and increased with depth, while A decreased with depth. Comparisons of creep rates for different permafrost environments suggest that ground temperature largely controls the magnitude of permafrost creep. Key words : permafrost, creep parameters, Tibet Plateau.

Analysis of Secular Variations of Geomagnetic Field in Lithuania Based on the Survey in 2016

2017 ◽  
Author(s):  
Arunas Buga ◽  
Simona Einorytė ◽  
Romuald Obuchovski ◽  
Vytautas Puškorius ◽  
Petras Petroškevicius
Keyword(s):  
Geomagnetic Field ◽  
Field Research ◽  
Field Measurements ◽  
Geomagnetic Observatory ◽  
Research Activities ◽  
Secular Variations ◽  
Geomagnetic Data ◽  
The Mean ◽  
Using Data ◽  
Magnetic Field Variations

Lithuania is successfully integrated in the European geomagnetic field research activities. Six secular variation research stations were established in 1999 and precise geomagnetic field measurements were performed there in 1999, 2001, 2004, 2007 and 2016. Obtained diurnal magnetic field variations at measuring station and neighbouring observatories were analysed. All measurements are reduced to the mean of the year using data from geomagnetic observatory of Belsk. Based on the measured data the analysis of geomagnetic field parameter secular changes was performed. Results of the presented research are useful for updating the old geomagnetic data as well as for estimation of accuracy of declination model.

scholarly journals An Adaptive Approach for Voltage Sag Automatic Segmentation

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3519 ◽  
Author(s):  
Xianyong Xiao ◽  
Wenxi Hu ◽  
Huaying Zhang ◽  
Jingwen Ai ◽  
Zixuan Zheng
Keyword(s):  
Automatic Segmentation ◽  
Field Measurements ◽  
Voltage Sag ◽  
Segmentation Method ◽  
Jump Point ◽  
Singular Value Decomposition Method ◽  
Research Activities ◽  
Power Quality Monitoring ◽  
The Mean ◽  
Value Decomposition

Voltage sag characterization is essential for extracting information about a sag event’s origin and how sag events impact sensitive equipment. In response to such needs, more characteristics are required, such as the phase-angle jump, point-on-wave, unbalance, and sag type. However, the absence of an effective automatic segmentation method is a barrier to obtaining these characteristics. In this paper, an automatic segmentation method is proposed to improve this situation. Firstly, an extended voltage sag characterization method is described, in which segmentation plays an important role. Then, a multi-resolution singular value decomposition method is introduced to detect the boundaries of each segment. Further, the unsolved problem of how to set a threshold adaptively for different waveforms is addressed, in which the sag depth, the mean square error, and the entropy of the sag waveform are considered. Simulation data and field measurements are utilized to validate the effectiveness and reliability of the proposed method. The results show that the accuracies of both boundary detection and segmentation obtained using the proposed method are higher than those obtained using existing methods. In general, the proposed method can be implemented into a power quality monitoring system as a preprocess to support related research activities.

scholarly journals A high resolution lithospheric magnetic field model over southern Africa based on a joint inversion of CHAMP, Swarm, WDMAM and ground magnetic field data

2018 ◽  
Author(s):  
Foteini Vervelidou ◽  
Erwan Thébault ◽  
Monika Korte
Keyword(s):  
Magnetic Field ◽  
Southern Africa ◽  
Field Model ◽  
Joint Inversion ◽  
Field Measurements ◽  
Magnetic Field Data ◽  
Magnetic Field Model ◽  
Lithospheric Magnetic Field ◽  
The Mean ◽  
Ground Magnetic

Abstract. We derive a lithospheric magnetic field model up to equivalent Spherical Harmonic degree 1000 over southern Africa. We rely on a joint inversion of satellite, near-surface and ground magnetic field data. The input data set consists of magnetic field vector measurements from the CHAMP satellite, across-track magnetic field differences from the Swarm mission, the World Digital Magnetic Anomaly Map and magnetic field measurements from repeat stations and three local INTERMAGNET observatories. For the inversion scheme, we use the Revised-Spherical Cap Harmonic Analysis (R-SCHA), a regional analysis technique able to deal with magnetic field measurements obtained at different altitudes. The model is carefully assessed and displayed at different altitudes and its spectral content is compared to high resolution global lithospheric field models. By comparing the shape of its spectrum to a statistical power spectrum of Earth's lithospheric magnetic field, we infer the mean magnetic thickness and the mean magnetization over southern Africa.

scholarly journals Retrieving Crop Leaf Chlorophyll Content Using an Improved Look-Up-Table Approach by Combining Multiple Canopy Structures and Soil Backgrounds

2020 ◽  
Vol 12 (13) ◽  
pp. 2139 ◽  
Author(s):  
Xiaojin Qian ◽  
Liangyun Liu
Keyword(s):  
Chlorophyll Content ◽  
Spectral Response ◽  
Canopy Structure ◽  
Field Measurements ◽  
Wide Field ◽  
Large Variability ◽  
Leaf Chlorophyll Content ◽  
Leaf Chlorophyll ◽  
Look Up Table ◽  
The Mean

Leaf chlorophyll content (LCC) is a pivotal parameter in the monitoring of agriculture and carbon cycle modeling at regional and global scales. ENVISAT MERIS and Sentinel-3 OLCI data are suitable for use in the global monitoring of LCC because of their spectral specifications (covering red-edge bands), wide field of view and short revisit times. Generally, remote sensing approaches for LCC retrieval consist of statistically- and physically-based models. The physical approaches for LCC estimation require the use of radiative transfer models (RTMs), which are more robust and transferrable than empirical models. However, the operational retrieval of LCC at large scales is affected by the large variability in canopy structures and soil backgrounds. In this study, we proposed an improved look-up-table (LUT) approach to retrieve LCC by combining multiple canopy structures and soil backgrounds to deal with the ill-posed inversion problem caused by the lack of prior knowledge on canopy structure and soil-background reflectance. Firstly, the PROSAIL-D model was used to simulate canopy spectra with diverse imaging gometrics, canopy structures, soil backgrounds and leaf biochemical contents, and the canopy spectra were resampled according to the spectral response functions of ENVISAT MERIS and Sentinel-3 OLCI instruments. Then, an LUT that included 25 sub-LUTs corresponding to five types of canopy structure and five types of soil background was generated for LCC estimation. The mean of the best eight solutions, rather than the single best solution with the smallest RMSE value, was selected as the retrieval of each sub-LUT. The final inversion result was obtained by calculating the mean value of the 25 sub-LUTs. Finally, the improved LUT approach was tested using simulations, field measurements and ENVISAT MERIS satellite data. A simulation using spectral bands from the MERIS and Sentinel-3 OLCI simulation datasets yielded an R2 value of 0.81 and an RMSE value of 10.1 μg cm−2. Validation performed well with field-measured canopy spectra and MERIS imagery giving RMSE values of 9.9 μg cm−2 for wheat and 9.6 μg cm−2 for soybean using canopy spectra and 8.6 μg cm−2 for soybean using MERIS data. The comparison with traditional chlorophyll-sensitive indices showed that our improved LUT approach gave the best performance for all cases. Therefore, these promising results are directly applicable to the use of ENVISAT MERIS and Sentinel-3 OLCI data for monitoring of crop LCC at a regional or global scale.

Prediction of floor responses to crowd bouncing loads by response reduction factor and spectrum method

2020 ◽  
pp. 136943322097556
Author(s):  
Jun Chen ◽  
Jingya Ren ◽  
Vitomir Racic
Keyword(s):  
Structural Damage ◽  
Response Spectrum ◽  
Field Measurements ◽  
Reduction Factor ◽  
Response Reduction Factor ◽  
Long Span ◽  
Single Person ◽  
Vibration Serviceability ◽  
Concert Halls ◽  
Structural Responses

Bouncing is a typical rhythmic crowd activity in entertaining venues, such as concert halls and stadia. When the activity’s frequency is close to the natural frequency of the occupied structure, the corresponding bouncing loads can cause intense structural vibrations resulting in vibration serviceability problems, even structural damage. This study suggests a method for prediction of vibration response due to crowd bouncing by a response reduction factor (RRF) in conjunction with a previously established response spectrum approach pertinent to a single person bouncing. The RRF is defined as a ratio between structural responses with and without taking into account synchronization of body movements of individuals in a bouncing crowd. The variations of RRF with number of persons, structural frequency, bouncing frequency and structural damping ratios have been studied using experimental records of crowd bouncing loads. Based on the findings a practical design curve for RRF has been proposed. Application of the proposed method has been validated on numerical simulations and field measurements of a long-span floor subjected to crowd bouncing loads.

Stiffness Design for Specified Nonexceedance Probability of Seismic Response

1998 ◽  
Vol 14 (1) ◽  
pp. 165-188 ◽  
Author(s):  
Yutaka Nakamura ◽  
Tsuneyoshi Nakamura
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Seismic Response ◽  
Amplification Factor ◽  
Design Method ◽  
Response Spectrum ◽  
Time History ◽  
Stiffness Design ◽  
The Mean ◽  
Shear Building

A direct procedure is presented for generating a response spectrum for an arbitrary nonexceedance probability from a prescribed design mean response spectrum. An amplification factor is derived to estimate the maximum response values of an MDOF system for a nonexceedance probability from the mean maximum ones. An efficient stiffness design method for a shear building is developed with the use of its fundamental frequency and translational eigenvector as parameters for adjusting the nonexceedance probability of the seismic drifts to the specified value. The validity and accuracy of the proposed method are demonstrated by a Monte Carlo simulation together with time-history analyses.

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